Compare any two graphics cards:
GeForce GTX 550 Ti vs Radeon HD 4870 1GB
IntroThe GeForce GTX 550 Ti has a GPU clock speed of 900 MHz, and the 1024 MB of GDDR5 memory runs at 1026 MHz through a 192-bit bus. It also is made up of 192 SPUs, 32 Texture Address Units, and 24 Raster Operation Units.
Compare all of that to the Radeon HD 4870 1GB, which features a clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 256-bit memory bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
Performance-wise, the Radeon HD 4870 1GB should theoretically be a small bit superior to the GeForce GTX 550 Ti in general. (explain)
Texel RateThe Radeon HD 4870 1GB should be a small bit (more or less 4%) better at texture filtering than the GeForce GTX 550 Ti. (explain)
Pixel RateThe GeForce GTX 550 Ti should be a lot (more or less 80%) faster with regards to AA than the Radeon HD 4870 1GB, and should be capable of handling higher resolutions without losing too much performance. (explain)
Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.
Memory Bandwidth: Bandwidth is the largest amount of data (measured in megabytes per second) that can be transferred past the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total number of texture units by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.